Device and method for sharing an immersion in a virtual environment

ABSTRACT

In a device ( 100 ) and a method implemented by said device, two immersive systems are connected such that a virtual environment generated on a source immersive system ( 10 ) is reproduced on a target immersive system ( 20 ). The images of the virtual environment displayed on the display system of the source immersive system are transformed in order to be displayed on the display system of the target immersive system, such that a virtual reproduction of the virtual environment is correctly represented on the target immersive system for an observer, irrespective of the structural and software differences between the two immersive systems. Freezing certain display data and observation conditions of the source system results in a temporary stabilisation of the representation of the virtual environment on the target system without any negative effect on the coherence of the representation on said target system.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the National Stage of International Application No.PCT/FR2017/051004, having an International Filing date of 27 Apr. 2017,which designated the United States of America, and which InternationalApplication was published under PCT Article 21(2) as WO Publication No.2017/187095 A1, and which claims priority from, and the benefit of,French Application No. 1659768, filed on 10 Oct. 2016, FrenchApplication No. 1659160, filed on 28 Sep. 2016, and French ApplicationNo. 1653758, filed on 27 Apr. 2016, the disclosures of which areincorporated herein by reference in their entireties.

BACKGROUND 1. Field

The present disclosure relates to the field of virtual reality and tothe presentation of virtual environments and virtual environmentsharing.

More specifically, the present disclosure relates to a device and amethod for sharing the immersion in a virtual environment with usershaving immersion means that are different from the means havinggenerated the virtual environment.

2. Brief Description of Related Developments

In the field of virtual reality, one or more users of a system forimmersion in a virtual environment are immersed in the virtualenvironment by means of a hardware environment generating stimuli toprovide users with sensations that are similar to, if not identical to,if not supposed to be, those that would be felt in a real environmentthat the virtual environment is intended to reproduce.

It is understood here that the representation is not necessarilyrealistic, but can also have some deformed, attenuated or exaggeratedeffects in order to produce specific sensations such as an enhancedperception of phenomena in the virtual world. For example, by means of ascale effect, a user can become immersed in a microscopic universe whichwould normally be inaccessible to him. A user can be immersed in orderto observe an environment that is not visible under ordinary conditions,such as an aerodynamic flow, or to observe a representation of anon-physical environment, such as a database viewed in 3D.

In some cases, the same virtual environment is shared between aplurality of users.

The paragraphs hereafter refer to a visual representation of the virtualenvironment, in two or three dimensions; they shall more specificallydescribe the problems and solutions related to this visualrepresentation in the context of the present disclosure.

One known solution for allowing at least two users to be immersed in avirtual environment consists of duplicating the data used to build thevisual representation of the virtual environment on two immersivesystems, whereby each system is allocated to a user, in order to obtain,on each of the two systems, a real-time rendering corresponding to thepoint of view of each user associated with a system. In such a case, theinformation regarding the position and/or the interactions made by eachof the users are synchronised in order to allow each of the virtualenvironments reproduced on each of the systems to be in an identicalstate.

One advantage of this solution is that it allows each of the userssharing the immersion to have their own point of view over the sharedvirtual environment.

Thus, a user that is immersed by means of a first immersive system canlook at the left side of an object, and a second user that is immersedin the same virtual environment by means of a second immersive systemcan simultaneously look at the right side of the same object.

In such a solution, each of the immersive systems must possess the dataused to build the virtual environment, and the visual representationthereof, and all of the applications, in particular the software,allowing this data to be exploited, which conditions require theimplementation of a data duplication step and the acquisition oflicenses, which can be expensive, for the software implemented on eachof the systems.

Moreover, when the two immersive systems are remote, data transmissionposes confidentiality problems, in particular in industrial environmentswhere the data carries a significant volume of information, which couldhave a sensitive nature, on the definition of the virtual environment,for example a digital model of a machine prototype.

Another drawback of this solution concerns the need for each immersivesystem to have digital processing systems with sufficient performancelevels to generate the images of the virtual environment in real time onthe display means of the immersive system, which performance levels mustbe even higher if the immersive system is to exploit a three-dimensionalenvironment and/or produce a three-dimensional representation.

Another drawback of this solution is that the comfort of sharing theexperience of the virtual world greatly depends on the quality of thenetwork communication means implemented. Since sharing is based on thesynchronisation of the data between a plurality of immersive systems,the latency times resulting from the network communication means affectthe speed at which the data originating from a remote immersive systemis updated in a given immersive system, thus causing potentiallysignificant disparity between the effective state of the virtualenvironment at a given moment in time of the remote immersive system andthat reproduced within the immersive system in question at the samemoment in time.

According to another known method, which avoids the transmission ofcertain sensitive data, images produced by an immersive system for auser are filmed by a camera worn by the user, oriented to show theimages in the user's visual field, and are transmitted for observationon a screen by individuals located close thereto or distant therefrom.However, this method does not provide the quality expected by a remoteperson observing a virtual environment since the image filmed isexploited on a single screen and since the image filmed generallycomprises defects and artefacts as a result of the implementation by theimmersive system of display systems for displaying the images comprisinga plurality of screens assembled to form the immersive environment.Moreover, the individuals observing the image remotely are passive andhave no interaction with said images. Furthermore, such a solutioncannot be considered when the immersive system implements a virtualreality headset, whereby the images are in this case displayed veryclose to the user's eyes.

In the case of an immersive system comprised of a plurality of screensand/or images combined to obtain one large field of view, one ofordinary skill in the art knows that the images are composed for viewingfrom a given location of the display system and if observed from anotherlocation, the images viewed are deformed and contain junction defectswhen implemented on a plurality of screens.

Thus, even when the display system of the remote immersive system isidentical to that of the immersive system generating the images of thevirtual environment, in order for the images displayed to be correctlyviewed by the remote observer, the position of his/her observation pointin the remote display system must be the same as that of the user'sobservation point in the display system of the immersive system. Theabove condition is, in practice, impossible to comply with since eachuser must be free to move their head, even to a small degree.

Non-compliance with this condition on the positions of the observationpoints produces inconsistencies in the different images displayed in theremote display system, with deformations and discontinuities that aregenerally unacceptable for the proper understanding of the informationdisplayed, and incompatible with performing an immersion.

SUMMARY

The present disclosure provides a solution to the different problems ofthe prior art in the field of the immersion of an observer in a virtualenvironment generated for another system.

One advantage lies in the fact that it avoids multiplied costs linked tosoftware licenses.

Another advantage lies in the fact that it avoids the need to duplicatedata and the data transmission restrictions.

Another advantage lies in the fact that the solution does not limit thechoice of the hardware architectures of each of the immersive systemsimplemented.

Another advantage lies in the fact that it preserves the confidentialityof the data of the virtual environment.

Another advantage lies in the fact that it preserves the quality of thevisual representation of the virtual environment and of the immersion ina remote system.

For this purpose, the present disclosure relates to a device for sharingan immersion in a virtual environment, comprising:

-   -   a source system, transmitting operating data for a visual        representation of the virtual environment, said operating data        comprising display data relative to images of said visual        representation and comprising data on the observation conditions        under which the visual representation of the virtual environment        was generated;    -   at least one target immersive system, comprising a digital        processing system transmitting images to at least one display        system of said target immersive system.

Moreover, the device comprises: transmission means 30 for transmittingthe operating data delivered by the source system 10 to the at least onetarget immersive system 20;

means for converting the display data, representative of images of thevisual representation of the virtual environment delivered by the sourcesystem 10 associated with data on the observation conditions, in orderto build images displayed in the display system 22 of the targetimmersive system 20, such that the set of images displayed by saiddisplay system of said target immersive system is the result ofprocessing operations intended to enhance the immersion on said targetimmersive system 20 in the display data upon passage from theobservation conditions transmitted by the source system 10 to effectiveobservation conditions in the display system 22 of said target immersivesystem.

In practice, as will be understood in the description hereafter,enhancing the immersion involves compensating for any potential visualdeformations resulting from the processing of display data on differentdisplay systems and/or according to different observation conditions.Enhancing the immersion can further involve modifying the position, inthe virtual environment of the target system, of the portion of contentof the virtual environment visible through the display system of thesource system to present it in a stabilised manner, reducing the impactof the frequent head movements of the user of the source system.

Sharing can take place in real time, whereby the data transmission iscarried out continuously, or can be in delayed time.

Furthermore, by having the target immersive system carry out theconversion of the display data for the part dependent on the effectiveobservation conditions, including the data on the position ofobservation and/or direction of observation, in the display system ofthe target immersive system, the impact of the latency time isminimised, said latency time occurring between the display in the targetsystem of the converted images and the processing thereof for theconversion of the display data from the effective observation point inthe display system of the target system.

In one embodiment, the source system is an immersive system comprising asource display system displaying images of the display data of a visualrepresentation of a virtual environment generated by said source system.

A system is thus obtained, wherein the operating data of the sourcesystem is generated with the interaction of a user of the sourceimmersive system, whereby the immersion can be shared in real time or indelayed time with an observer of the target system.

In one embodiment, the conversion of the display data comprises areconstruction of a 3D virtual representation of a source display systemof the physical environment of the source display system, a position ofan observation point of the observer in the display system of the targetsystem being forced, for the conversion of the display data, to take thesame position in said 3D virtual representation of the source displaysystem as the position of observation of the user in the source displaysystem.

In one embodiment, the source immersive system comprises a measuringsystem for measuring, in real time, the direction of observation, and/orthe position of observation, in the display system of the sourceimmersive system, of a user that would be immersed in the virtualenvironment of said source immersive system, and the at least one targetimmersive system comprises a measuring system for measuring thedirection of observation, respectively and/or the position ofobservation, in the display system of said target immersive system, ofan observer that would be immersed in the virtual environment displayedon said target immersive system.

An effective position and/or direction is thus known, from which thedisplay data of the images displayed in the display system of the sourceimmersive system have been generated for viewing by the user and aneffective position and/or direction from which the display data of theimages displayed in the display system of the target immersive systemmust be generated in order to be viewed by the observer and berepresentative of the virtual environment viewed by the user of thesource immersive system.

Software for the partial processing of the display data can be executedon the digital processing means of the source immersive system, or on anancillary computer connected to a network via which data is transmittedbetween the source system and at least one target immersive system, saidsoftware converting the display data generated by the source immersivesystem, representative of the images of the visual representation of thevirtual environment of the source system, into display datacorresponding to independent non-dimensional images of a structure of aviewing system that is to display the images, said display datacorresponding to non-dimensional images being transmitted to the atleast one target immersive system.

In this configuration, the conversion calculations for the display datathat does not depend on the target immersive system are advantageouslyconnected to the source system or to an independent ancillary computer.Such a solution allows, in a device comprising a plurality of targetimmersive systems, for the transmission to the different targetimmersive systems of the display data in a neutral, non-dimensionalform, for which only the subsequent processing, specific to the targetimmersive system, is carried out by each of the target immersivesystems.

In one embodiment, the non-dimensional images correspond to imagesprojected onto an inner wall of a sphere, at the centre of which spherethe observation point of the source system is placed, in order to formthe non-dimensional images in a solid angle corresponding to the imagesdisplayed on the viewing system of the target immersive system andcapable of reaching four Pi steradians.

An observer of a target system can thus select a direction ofobservation in any direction in space without being limited by a“visual” field of the source system.

In order to assist the observer of a target immersive system in choosinga direction of observation in a virtual environment, the representationconditions whereof he/she does not have full control over, symbolicrepresentations are advantageously superimposed over the visualrepresentation of the virtual environment shown on the target immersivesystem to provide the observer with an orientation aid and aid inselecting a direction of observation.

These symbolic representations comprise, for example, the graphicalmaterialisation of a sphere or of a grid associated with therepresentation of horizontal surfaces, for example a floor, and/orvertical surfaces, for example a wall.

Such symbolic representations, which can possibly be materialised solelyon a temporary basis, for example when instructed by the observer, orunder certain conditions, for example in the case of a fast evolution inthe observation conditions of the source system, assist the observer foreasier selection of the direction of observation and for identifying orlocating his/her position in the virtual scene.

The display data processing software for building images displayed onthe one or more screens of the display system of the at least one targetimmersive system can also be executed on the computing means of saidtarget immersive system.

In such a case, the source system transmits the same data to all targetimmersive systems and the digital processing operations for theconversion of the display data are carried out by each target immersivesystem as a function of the configuration specific thereto and of localvariables, such as the position and directions of observation of theobserver in the display system of the target immersive system.

In one embodiment, the device comprises a plurality of target immersivesystems simultaneously connected to the source immersive system. It isthus possible, thanks to the advantages of the present disclosure, toallow numerous observers, who can be located remotely and in scatteredlocations, to follow the immersion experienced by a user of the sourcesystem.

It is understood that a target immersive system can be situated at anydistance from the source system, whereby the problems involving thesynchronisation of the visual representation displayed in the targetimmersive system with the observation conditions of the observer arespecifically overcome by the present disclosure.

In one embodiment, the source system comprises equipment for acquiring adigital or analogue signal, carrying display data, generated by thesource system and which transmits, in a digital data format, saiddisplay data corresponding to the signal acquired, directly orindirectly, to at least one target immersive system.

This thus prevents the need for any intervention or modification to thehardware or software of the source immersive system, other than theconnection of said acquisition equipment, whereby such interventions ormodifications, where possible, are often burdensome.

In one embodiment, the source immersive system comprises software,executed on a digital processing system, for acquiring content of thedisplay data of the source system, after the display data has beencomputed, and which transmits, in a digital data format, said content ofthe display data acquired, directly or indirectly, to the at least onetarget immersive system.

In these embodiments, such content advantageously corresponds to a dataset that is sufficient for reproducing the images generated by thesource system. Said data is, for example, the digital data sent to adisplay system of the source system, where relevant before analogueconversion, or data subjected to spatial and/or temporal compressionalgorithms for reducing the size thereof, or sets of attributes of eachimage: contours, textures, colours, etc.

The content is made up, for example, of images, or video streams, in yetanother embodiment of stereo images, and in another example embodimentof a stereo video stream.

Advantageously, when looking to synchronise the source system and theone or more target immersive systems, a content format is determined asa function of the computing means of the source system and/or of the oneor more target immersive systems, and as a function of the datatransmission means, so as to limit lag between the processing operationson the operating data by the source system and by the one or more targetimmersive systems as much as possible, while taking into account theperformance levels of the equipment implemented by the entire datatransmission chain and the processing operations carried out on saiddata by the systems.

In one embodiment, the device comprises a data recording system,configured to record the operating data generated by the source systemand for transmitting said operating data to at least one targetimmersive system in delayed time.

An immersion recorded on a source system can thus be replayed at anytime and any number of times on any target immersive system.

In one embodiment, the source system comprises image processing softwareand a source display system, and a target immersive system comprisessoftware for image synthesis and for generating a visual representationof a virtual environment in the form of images displayed on one or morescreens of the display system of said target immersive system andfurther comprises equipment and/or software for acquiring the displaydata corresponding to the images displayed on the display system of saidtarget immersive system, such that each of said target and sourceimmersive systems can alternate between being a source system and atarget system. In this embodiment, the device is shown to beparticularly well suited to collaborative works carried out by a userand an observer capable of reversing their roles.

In this configuration, the hardware and software configurations of thetwo target and source immersive systems capable of reversing theirconditions can be different, whereby the device according to the presentdisclosure bypasses the compatibility conditions in these areas oftenencountered with known systems. This configuration is also compatiblewith the simultaneous connection of other target immersive systems.

In one embodiment, the display system and the processing system of thetarget immersive system and/or of the source system are associated withinteraction means configured such that they modify, via the displaysystem and/or the processing system of the given immersive system, thecontent and/or the behaviour of the images displayed by the displaysystem of the source system or of the given target immersive system.

Thus, each user of the source system and observers of the targetimmersive system have means for intervening with regards to thebehaviour of the displays without detriment to consistency.

In one embodiment, the interaction means comprise a freeze command forselectively activating and deactivating the freezing of all or part ofthe display data and/or of the observation conditions used to generatethe images to be displayed by the display system of the source systemand/or of the target immersive system.

The observer of the target system, who does not have any means forcontrolling the operation of the source system, can thus freeze, atleast momentarily, certain data of the representation of the virtualenvironment of the source system, for example in order to perfect ananalysis.

In one embodiment, the interaction means of the target immersive systemcomprise a freeze command for freezing a subset of observationconditions in the display system of the source system and/or of thetarget immersive system.

In one embodiment, the interaction means of the at least one targetimmersive system are moreover configured for pointer use and/or for theannotation of the images displayed by the display system of said targetimmersive system.

The annotations are, for example, materialised in the form of inlayswithin the images.

In one embodiment, data characterising the pointing operations orannotations formed on images of a target immersive system aretransmitted via the transmission means to at least one other connectedimmersive system. This other system, which is the source system oranother target system, receiving this data can thus process this datafor the display thereof.

The interaction means comprise, for example, one or more touch-sensitivesurfaces or surfaces that are sensitive to the presence of a hand orfinger, and/or one or more pointers.

The potential display system of the source system, and the displaysystem of the at least one target immersive system, each belong to oneof the categories among the group implementing flat screens and/orcurved screens:

-   -   multi-sided display systems;    -   virtual reality, augmented reality or mixed viewing headsets;    -   multi-screen display systems;    -   screens;    -   screens carried by a user or observer.

The configuration of the device can thus be adapted to suit numeroustypes of needs, in particular as a function of the cost, deploymentspeed and realism criteria for the graphical representations.

These categories, independently from the dimensions and shape of thescreens, which can be flat or curved, can coexist inside the device ofthe present disclosure, whereby only the conversion calculations for thedisplay data is modified to suit the specificities of the screens and ofthe display systems.

In one embodiment, at least one target immersive system is situated in alocation that is remote from the source system, the physical separationof the two systems being such that the user of the source system and theobserver of the target immersive system are not capable of communicatingwith one another without using technical communication means. In thisconfiguration, spatial limitations are extended, which allow the sharingof an immersion.

In one embodiment, at least one target immersive system is situated inthe vicinity of the source system, the physical separation being suchthat a user of the source system and an observer of the target immersivesystem can communicate directly with one another without any physicalbarrier, i.e. without the need to use technical means. It is in thisconfiguration that a shared immersion is obtained, for example withinthe scope of collaborative works, without suffering from the inevitableartefacts produced when an observer is located in the vicinity of theuser in the hope of feeling the effects.

Such a configuration is not only hypothetical insofar as it allows forthe simulation, including at the same location, of the immersion, withsimple hardware means, for one or more observers, in the virtualenvironment of the user of the source system, on the one hand withoutdisrupting said user and on the other hand under optimum conditions,since an observer cannot position himself/herself in the display systemof the source system under the same observation conditions as those ofthe user.

The present disclosure further relates to a method for sharing animmersion in a virtual environment of an observer in a target immersivesystem, comprising the steps of:

generating, independently from the target immersive system, operatingdata for a visual representation of the virtual environment, saidoperating data comprising display data relative to images of said visualrepresentation and comprising data on the observation conditionsassociated with said display data;

displaying, on a display system of the target immersive system, imagesrepresenting the virtual environment.

According to the present disclosure, the method comprises, for eachimage or set of images to be displayed, between the generation step andthe display step, a conversion step, carried out at least partially onthe target immersive system, for converting display data of the virtualenvironment generated in the generation step, the conversion stepcomprising the determination of the effective observation conditions ofthe operator in the display system of the target immersive system andthe conversion of the display data associated with the observationconditions of the display data generation step, into display datacorresponding to the effective observation conditions of the observer.

The display data generated by the source system, the display data beinggenerated for observation conditions that are independent from thetarget immersive system, can thus be converted into display datacorresponding to images adapted to suit the display system of the targetimmersive system and the observation conditions of an observer of saidtarget immersive system in order to present the virtual environment tosaid observer.

In one embodiment, each image point of an image converted in theconversion step for display by the display system of the targetimmersive system, is determined as a function of at least one effectiveobservation point in the display system of the target immersive systemin order to preserve, to within a constant proportionality factor forthe entire image at a given moment in time, a same relative direction ofobservation relative to any other image point of said converted image,observed from the effective observation point, as the relative directionbetween said image points in the display data of the visualrepresentation of the virtual environment generated in the generationstep, delivered by the source system and comprising the image data andthe data on the observation conditions associated with said image data.

In one embodiment, the step of generating the display data for therepresentation of the virtual environment is carried out on a sourcesystem, which source system is: an image generation system for a virtualdisplay; or a system for broadcasting a stream of real or virtual imagesgenerated in real time or recorded; or an immersive system in which auser is immersed.

In one embodiment, the reconstruction of a 3D virtual representation ofthe source display system of the physical environment of the sourcedisplay system is carried out by the source immersive system or by theancillary computer connected to the network. In one embodiment, theconversion of the display data comprises a reconstruction of a 3Dvirtual representation of the source display system, a position ofobservation of the observer being forced, for the conversion of thedisplay data, to take the same position in said 3D virtualrepresentation of the source display system as the position ofobservation of the user in the source display system.

According to this embodiment, a virtual source display system iscreated, the position whereof relative to the observer is reproducedfrom the position of the user in the real source display system.

The display system of the source immersive system is reconstructedvirtually on the target immersive system, which virtual reconstructionis displayed on the display system of the target immersive system suchthat the observation conditions of the observer of said virtualreconstruction of the source system in the target immersive systemcorrespond at least partially to the observation conditions of the userof the source immersive system in the source immersive system.

This conversion removes the need to duplicate the data of the virtualenvironment and can be applied to any form of target immersive systemand for any software executed on the source immersive system.

In one embodiment, the display data conversion step is carried out inits entirety on the target immersive system after a step of convertingthe observation conditions and display data of the virtual environment,generated by the digital processing system of the source immersivesystem.

In another embodiment, the display data conversion step is carried outin part on the source immersive system, or on an ancillary computerconnected to a network of the data transmission means, before a step oftransmitting the observation conditions and partially converted displaydata of the virtual environment to the target immersive system, and thetarget immersive system converts the partially converted display data asa function of the operating data of the target immersive system in orderto form the images displayed on the target display system.

Advantageously in such a case, the display data partially converted bythe source immersive system, or the ancillary computer, is independentfrom the features and operating data of a target system, thus allowingthe processing step to be factorised, or even reduced to a simpleprocessing operation for display on certain target systems.

In one embodiment, the conversion step comprises a freezing step forfreezing the display data of the representation of the virtualenvironment or for freezing the observation conditions, generated duringthe generation step.

In one specific embodiment, the data of the observation conditions inthe display system of the target immersive system continue to be takeninto account during the display data freezing or observation conditionsfreezing step.

It is therefore possible to maintain, for the user of the source system,a perception of the virtual environment generated by the sourceimmersive system, while preserving, in the target immersive system, acorrect and stable view of said virtual environment placed in thisfrozen condition despite variations in the observation conditions insaid source immersive system. The display data in the target immersivesystem is thus interpreted as if the virtual environment was completelystatic and the user of the source system was no longer moving, thusresulting in a kind of 3D acquisition of the state of the sourceimmersive system.

The observer is able to freeze, at least partially, the representationof the environment on the target system, and momentarily obtain a stableimage on which annotations, for example, can be made.

In one embodiment, the method comprises an initialisation step in whichthe target immersive system initialises a register comprising data onconditions under which the display data is generated during thegeneration step.

In another embodiment, the display data conversion step is carried outin part on the source immersive system, or on an ancillary computerconnected to a network of the data transmission means, before a step oftransmitting the partially converted display data of the virtualenvironment to the target immersive system, which target immersivesystem converts the partially converted display data as a function ofthe operating data of said target immersive system.

BRIEF DESCRIPTION OF THE DRAWINGS

The description of the present disclosure is provided with reference tothe figures which diagrammatically illustrate, in a non-limiting manner:

FIG. 1 : a simplified example of a device for sharing an immersion in avisual environment with a source immersive system comprising a displaysystem of the multi-screen type and a target immersive system of thesingle flat-screen type;

FIG. 2 : an illustrated example of the conversion principles forconverting an image, generated in a source immersive system with adisplay system and observed in a target immersive system with adifferent display system, for preserving the visual immersionconditions;

FIG. 3 : an illustration of a device comprising a plurality of targetimmersive systems with display systems implementing differenttechnologies and reproducing the virtual environment of the same sourceimmersive system;

FIG. 4 : a simplified block diagram of the method according to thepresent disclosure.

DETAILED DESCRIPTION

In the description, the terms and expressions hereafter must beunderstood as defined below:

-   -   Immersive system: A system intended to reproduce, in real time,        sensory impressions for a user through stimulation means        appropriate for the sensations to be reproduced. A visual        immersive system generally comprises a set of hardware and        software means in order to at least: generate images of a visual        representation of a virtual environment; display images intended        for at least one user; the images displayed being generated such        that they represent the virtual environment as it must be        perceived by the user according to his/her virtual environment        observation conditions.

Display system: set of hardware means and, if necessary software means,comprising means for displaying images, for example one or more displayscreens arranged between one another in space in order to display theimages to a user or to an observer, if necessary implementingconventional optical systems such as mirrors, beam splitters, opticalcollimating elements, filters, etc. The display system is associated, ifnecessary, with means for determining, in real time, in a system ofreference linked to the screens, the position and/or the direction ofobservation, of a user or of an observer, looking at the imagesdisplayed by said screens.

Headset: the specific case of a display system wherein the screens areattached to a support worn by the operator on his/her head. In thisspecific case, the position of observation is fixed in the system ofreference linked to the screens and the direction of observation is afunction of the eye movements. This type of equipment can be associatedwith means for tracking, in real time, the orientation, or even theposition, of the head in the physical environment, which will obviouslynot modify the position of the operator's head relative to the displaysystem, but could be used by the calculation software for generating therepresentation of the virtual environment to change the position anddirection of observation in a system of reference of the virtualenvironment.

Image: any form of visual representation shown on a screen. An image canbe still, or moving as a result of a succession of images in time, andcan result from a video stream, etc. An image can be transmitted, with aview to the display thereof on a screen, by an analogue signal or by adigital data set representing all or part (for example in the case ofcompressed signals) of an image, or both according to a given locationin the image transmission chain between the generation of the image andthe display thereof.

Virtual environment: an environment defining a digital data set definingthe features of this environment and necessary for the construction of avisual representation of this environment as it must be perceived. Thevirtual environment can be the result of a 2D or 3D construction basedon a digital model. The virtual environment can also be the result ofthe virtualisation of a real environment, for example by digitisedimages or video streams. The virtual environment can also be acombination of a digital model and a real environment according to anaugmented reality principle.

Immersion: a situation wherein representations of a virtual environmentare presented to one or more individuals so as to provide theseindividuals with the impression that they are physically surrounded bythe information contained in the virtual environment. In order toenhance the sensory impressions, the display system can comprise asystem for reconstructing depth perception, for example shutter glassessynchronised with the images displayed to present the user of theimmersive system with images corresponding to each of his/her eyes inorder to produce a stereoscopic effect.

In particular, the present disclosure considers the case of a virtualenvironment, the visual representation whereof is reproduced by theimmersive system by means of a display system.

The virtual environment reproduced can be two-dimensional, 2D, orthree-dimensional, 3D.

The digital information used by the immersive system can correspond, andoften corresponds, to data of a three-dimensional 3D immersiveenvironment, in which case a software application of the immersivesystem is an image synthesis application, which produces, at each momentin time, one or more new synthesis images by digital processing of the3D information as a function of a position of an observation point, forexample corresponding to an optical centre of a lens of a virtualcamera.

The digital information can also be data of a two-dimensional 2Denvironment such as films, potentially pre-recorded panoramic films,which can be digitally processed by a software application fordisplaying images viewed from an observation point controlled by theuser or controlled by a more or less interactive logic.

One of ordinary skill in the field of virtual reality knows theprinciples and mode of operation of the immersive systems that arecurrently widely used in numerous industrial applications, for examplein computer-aided design, in simulators and training systems, and ingaming applications generally categorised by the expression “videogames”.

The description of these known immersive systems will therefore not bedescribed in detail in this application; at most, elements, parts orsub-assemblies and principles will be referred to when considered usefulto the understanding of the description or when the immersive system ofthe present disclosure could be considered at risk of not beingunderstood according to the most conventional meaning of this term. Inparticular, in the present disclosure, a single screen of a computer orvideo monitor, or of a smartphone, can form the display part of adisplay system of an immersive system.

Moreover, in the example embodiment described, only the visual aspectsof the immersion will be considered, whereby the other aspects thereof,for example the audio aspects, are not covered or are only brieflymentioned.

For the data exchanges taking place between the systems, the followingexpressions will be used in the description:

“operating data”

“observation conditions data”

“display data”.

The operating data comprises the set of information of a representationof the virtual environment viewed in a viewing system by an observer,which situation can be real or virtual.

The operating data comprises the observation conditions data and thedisplay data.

The display data in particular comprises information regarding theimages generated by a source system 10.

For example, the display data comprises attributes for each of the imagepoints of the images generated by the source system 12, these attributesin particular comprising, in addition to the luminance and colourfeatures, the position of the image point in an image, for example animage to be displayed in said display system.

The display data is, for example, information contained in video frames.

The observation conditions data comprises in particular data regardingthe position from which and the direction in which a user or an observeris looking in a system for displaying the images, or with which imageshave been generated, for example by an image capture device capturing areal environment that is then virtualised.

FIG. 1 shows, as an example embodiment, a device 100 comprising twoimmersive systems, a source immersive system 10 and a target immersivesystem 20, connected by data transmission means.

The source immersive system 10 in FIG. 1 is a known system thatcomprises, in the example shown, a digital processing system 11,comprising a permanent or temporary database 11 a, used to store digitalinformation defining a virtual environment, and a display system 12 fordisplaying images generated by the digital processing system.

The digital processing system 11 is, in practice, a computer, the powerwhereof is suited to the real time image generations, on which imagesynthesis software is executed.

In a known manner, the database 11 a, in practice a memory or a filestorage system, contains a set of data defining the virtual environmentand required to generate a visual representation of said virtualenvironment.

The database further comprises data relative to the source immersivesystem itself, in particular parameters relative to the display system12, including the dimensions, positions and shapes of screens (12 a, 12b, 12 c, 12 d), on which are displayed the images used to form arepresentation of the virtual environment in which a user 90 isimmersed.

It should be noted that, in addition to the data on the virtualenvironment and the parameters of the display system 12, the computingmeans 11 further receive values of variables, generally as a function ofa user 90 under immersion conditions and/or of an operator of theimmersive system, which are required by the software for imagesynthesis.

The variables in this instance comprise a position of observation and adirection of observation of the user 90 in a system of reference of thedisplay system 12, on which position and direction of observation dependthe images representing the virtual environment to be displayed on thesescreens in order to present, as seen by the user, a correctrepresentation of said virtual environment from a position in saidvirtual environment in which the user is supposedly positioned.

Since the position and direction of observation must be known in orderto generate each new image displayed, said position and direction ofobservation are, in a manner known by one of ordinary skill in the art,measured or estimated in real time or assumed.

Such variables are, for example, commands sent to the digital processingsystem 11, for example by the user 90 by means of control members, inorder to act directly or indirectly on the virtual environment.

It is understood here that the variables are processed in a cyclicmanner by the software application carrying out the synthesis of thevirtual environment in order to present, in real time, i.e. with alatency and refresh time suited to the desired immersion, a point ofview in the virtual environment corresponding to an observation point ofthe user 90 in the display system of the physical immersive system.

The display means 12 of the source immersive system 10 in FIG. 1comprise a plurality of screens 12 a, 12 b, 12 c, 12 d forming amulti-sided system with four screens, in the example shown, often calledCAVE in the field of virtual reality, determining a volume in which theuser 90 can stand and move.

It should be noted that the dimensions of this example are not imposedand that any form of display system, whether multi-sided or otherwise,can be implemented, in particular depending on the advantages obtainedto achieve the immersion objectives.

For example, an L-shaped arrangement of two vertical screens enhancesvertical immersion. For example, an arrangement with three, four or fivescreens with angles of greater than 90° enhances the immersion of aplurality of users simultaneously. Certain screens can also be curved,cylindrical or spherical, and can prevent or reduce the number of screenjuxtapositions forming angles. The screens can also be worn by the userby means of equipment such as viewing headsets, which can be more orless transparent depending on the desired result regarding theperception of the surrounding physical environment.

The source immersive system 10 belongs, in the context of the presentdisclosure, to a device 100 further comprising at least one targetimmersive system 20.

The target immersive system 20 comprises at least one digital processingsystem 21 and one display system 22. The target immersive system can besimilar or even identical, in the structure and means thereof, to thesource immersive system 10, or different therefrom.

In particular, the display system 22 of the target immersive system 20can be identical to the display system 12 of the source immersive system10, or conversely can be different therefrom, for example by the numberof screens implemented, and/or by a shape of the screens, and/or by thesize of the screens, and/or by an arrangement of the one or morescreens, and/or by the fact that the one or more screens are carried ornot carried by the user and/or by the capacity or incapacity toreproduce images for a stereoscopic observation.

In the example of the device 100 diagrammatically illustrated in FIG. 1, the display system 22 of the target immersive system only comprises asingle screen 22 a, whereas the display system 12 of the sourceimmersive system comprises four thereof.

The screen 22 a, as the sole screen of the display system 22 in theexample embodiment shown in FIG. 1 , is, for example, a projectionscreen, or a conventional video screen, television or computer screen,or even a smartphone screen.

The digital processing system 21 of the target immersive device 20mainly comprises a memory, or a local database, which is used to storefeatures of the source immersive system and of the target immersivesystem used to convert display data corresponding to the images, and adigital computer on which display data processing software is executed,the principles whereof are described at a later stage in thedescription.

For simplicity purposes in the description hereafter, the terms “source”and “target” will be used to denote the elements of the source immersivesystem 10 and of the target immersive system 20 respectively. Dependingon the context, the source immersive system 10 can be referred to as the“source system” and the target immersive system 20 can be referred to asthe “target system”.

The device 100 further comprises data transmission means 30 fortransmitting data between the source system 10 and the target system 20.

Such data transmission means 30 consist of all known means in the datatransmission field for transmitting data between computers, and whichwill be, in the case of the present disclosure, chosen as a function ofthe data flow that must be obtained, the distance between the immersivesystems of the device, the number of connected systems and the availableresources in terms of communication means. In one embodiment, the datatransmission is carried out by a communication network such as theInternet network and the implementation of communication protocols andinterfaces suited to this network. The data transmission can alsoimplement different types of optical connections, radio connections, andwired connections.

The description hereafter is made with reference to the operation of thedevice 100 when the source system 10 generates the display data of avirtual environment, the images whereof are displayed on the sourcedisplay system 12, in which virtual environment the user 90 is immersed,and when said source system transmits, to the target system 20, datarelative to the display data generated by the source digital processingsystem 11.

It should be noted that the detailed description only makes reference toa single target system for simplicity purposes; however, the device 100can comprise any number of target systems, whereby all target systemsare independent from one another, can take on different structures, andoperate in a similar manner with the data received from the sourcesystem.

During operation of the device 100, the image generation softwareexecuted on the source digital processing system 11 generates arepresentation of the virtual environment in which the user 90 of thesource system is immersed, and produces display data for saidrepresentation of the virtual environment for each of the differentscreens 12 a, 12 b, 12 c, 12 d of the source display system 12.

This display data is generated as a function of the parameters capableof modifying the visual perception of the virtual environment by theuser 90, in particular as a function of a position in space of a pointfrom which the user 90 views each of the screens 12 a, 12 b, 12 c, 12 dof the source display system 12 and a direction of observation in whichthe user is looking, the direction of observation corresponding to anoptical axis of the observation means, in practice of the eyes. Thisposition and this direction associated thereto are generally referred tohereafter as the “observation point”.

The observation point can be a single point and, for example, correspondto an intermediate position between the two eyes of the user 90.

The observation point can also be dual when looking for depth perceptionthrough binocular vision; thus, the position of each eye of the user 90determines one observation point.

It should be noted that, in order to perform the computationscorresponding to the generation of the display data corresponding to theimages displayed on each of the screens, the digital processing systemassociated with the display system must possess data relative to thefeatures and arrangement of the different screens of the display system.

The images generated are displayed on the corresponding screens.

The operating data generated by the source system is transmitted, viathe data transmission means 30, to the target system.

It should be understood that said operating data can be transmitted inany data format according to a protocol understood by the target systemand that allows the display data and the associated observationconditions to be reproduced.

However, the operating data generated by the source system cannotdirectly produce the images displayed correctly on the target displaysystem 22, in particular as a result of the structural differencesbetween the source and target display systems, and/or the observationconditions attributed to the user 90 and to the observer 91respectively, in each of the source and target systems, which are notcorrelated.

More specifically, even for the hypothesis wherein the source and targetdisplay systems are identical, the observation point, and thus theobservation conditions, of the observer 91 in a system of reference ofthe target display system 22 cannot in practice be kept constantlyidentical to the observation point of the user 90 in a system ofreference of the source display system 12, and supposing that thedisplay data generated by the source system is displayed directly in theform of images on screens of the target display system, they would givean observer 91 of the target system a deformed, or even unexploitableview of the virtual environment.

By way of illustration of a simple situation wherein the source andtarget display systems are identical, an image of a straight line in thevirtual environment, which would be generated in the source system 10for display on two screens, the display surfaces whereof are notcoplanar, would appear as a broken line to an observer of the targetsystem 20, the observation point whereof would be different from thathaving been used to generate the display data in the source system.

In order to present the observer 91 of the target immersive system witha consistent representation of the virtual environment in which the userof the source system is immersed, each image through the operating datareceived by the target system from the source system is converted bydisplay data processing software as a function of the observationconditions in the source system of the target system. The imageprocessing software is preferably executed, at least partially, by thetarget digital processing system 21.

As will be understood in the description hereafter, a part of the imageprocessing operation can also be carried out by the source system, or byany system having the capacity to communicate with the source and targetsystems for receiving and transmitting the necessary data.

The display data conversion mainly consists of virtually reconstructingthe physical environment of the source display system 12 and in forcingthe observation point of the observer 91 to take the same position inthe virtual source environment as the observation point of the user 90in the source display system 12.

According to this principle, as shown in FIG. 2 , a 3D virtualrepresentation of the source display system 12′ is created in the targetsystem 20, as a function of the parameters of the source display system12, on virtual screens 12′a, 12′d, 12′c, from which virtualrepresentation of the source display system are displayed the images ofthe display data received corresponding to each of the real screens 12a, 12 d, 13 c of the source system, see FIG. 2 . A 3D virtualenvironment is thus formed in the target system, said environmentrepresenting, at all times, to within the latency time, the sourcedisplay system 12 with its visual representation of the virtualenvironment of the source system.

The target system 10 thus digitally processes the 3D virtualrepresentation of the source display system 12′ to construct a visualrepresentation therefrom on the target display system 22 as a functionof the observation conditions of the observer 91 of the target system,in which visual representation on the target display system, theeffective position and orientation, either measured or assumed, ofobservation in the target display system are also the position andorientation of observation in the 3D virtual representation of thesource display system and which correspond to the effective positionsand orientations, either measured or assumed, of observation of the userin the real source viewing system, as shown in FIG. 2 , where a centre40 of the projections corresponds to both the virtual observation pointin the 3D virtual representation of the source system and to theeffective observation point in the target system 22.

The digital processing operation in such a case corresponds to 3Dprojections of the images of the 3D virtual representation of the sourcedisplay system 12′ on the one or more screens of the target displaysystem 22, said projections having a centre 40 of projection made up ofthe position and orientation of observation, in the 3D virtualrepresentation, of the observer 91.

The target system 20 thus presents the observer 91 with a virtual sourcesystem in that it reproduces the behaviour, at any time, for the imagesdisplayed of the virtual environment, of the source system 10 and inthat it ensures that, regardless of the position and orientation of theobserver 91, said observer has a position and orientation in the 3Dvirtual representation of the source display system 12′ that isidentical to that of the user 90 in the source system 10, even thoughthe source and target systems can have different configurations and eventhough the user 90 and the observer 91 have observation conditions thatare, in practice, changing independently in their respective immersivesystems.

For example, in order to generate a consistent representation of thevirtual environment on the target immersive system, the observationspoints of the user 90 of the source system and of the observer 91 of thetarget system are superimposed in the 3D virtual representation of thesource display system 12′ and taken to be the centre 40 and a referenceaxis 41 of a spherical coordinate system used to produce theprojections. Each image point 121 of the real 12 or virtual 12′ sourcedisplay system in a given direction 42 from the observation point 40corresponds to an image point 221 of the target display system 22 in thesame direction and the image point 221 in the target system thus usesthe features (colour, luminosity, etc.) of the image point 121 of thesource system. Naturally, this condition is only valid if the two imagepoints visually superimposed in the two immersive systems exist.

If, during these projections, an image point of the source system doesnot have any projection equivalent in the target system, it cannot bedisplayed in said target system. Conversely, if an image point of thetarget system does not have a projection equivalent in the sourcesystem, the image point in said target system will correspond to a“blank” area in the display of the target system.

If the display data generated by the source system 10 has been processedaccording to the aforementioned principles, the images are displayed bythe target system 20 on the one or more screens of the display system ofsaid target system.

It should be noted that the position and orientation of the observer 91of the target system relative to the target display system 22 formparameters that are taken into account when carrying out the conversionof the display data. This consideration is necessary to ensure that thevirtual environment is represented in a manner consistent with the pointof view from which it was generated on the source system, and that thedesired immersive effect is reproduced on the target system.

However, for the reconstruction of the display data on the target systemto be consistent, the condition regarding the superimposition of thepositions of observation is necessary, whereas the condition regardingthe superimposition of the directions of observation is optional, saidlatter condition only being justified when the visual representationviewed by the observer 91 in the target system 20 is desired to be thatof the user 90 in the source system, including in terms of direction.

If only the positions of observation are kept identical, the observer 91in the target system is able, within the limits of the solid angle ofthe space in which an image is displayed, to view the representation ofthe virtual environment in a direction that is different from that inwhich the user 90 is looking at this virtual environment in the sourcesystem, however that corresponds to the visual representation that saiduser would have obtained in the source system had he/she been looking inthe same direction as the observer in the target system.

It must therefore be understood that, depending on the desired effect,only the data relative to the position of the observation point alone,or that relative to the position of the observation point combined withthe direction of observation, can be exploited.

The position of the observation point and the orientation of observationof the observer 91 are determined, for example measured in real time andtransmitted to the target digital processing system 21, in order to betaken into account in the display data conversion computations. Ifnecessary, the position and/or the direction of observation are simplyestimated or assumed. For example, when a plurality of observers arelooking at the one or more screens in the display system of the targetsystem, mean values of the observation conditions of the differentobservers can be calculated or assumed, it being understood that this isa compromise that will inevitably lead to distortions in the imagesdisplayed by the target system that could be perceived by certainobservers.

A target system 20 is thus produced, allowing an observer 91 to beimmersed in a virtual environment created by a source system 10, whichcan be remote.

This result is obtained without the transmission of data in the database11 a implemented by the source system, including with a target system20, the configuration whereof, in particular that of the display system,is different from that of the source system 10. Among otherpossibilities, it allows a digital processing system 21 to beimplemented in the target system 20, said digital processing systemhaving performance levels that are lower than those required by thesource system 10 to generate the virtual environment. It does notrequire the implementation of expensive image synthesis software. Itdoes not require the display systems of the source and target systems tobe compatible with one another, nor does it require that the observer 91maintains the observation conditions imposed in the target viewingsystem 22 in order to view the images as the user 90 perceives them inthe source display system 12.

The embodiment of the device 100 described is only cited by way ofexample.

The hardware architectures of the source system and of the one or moretarget immersive systems can be different from those illustrated in thedescription for carrying out the same functions.

The conversion of the display data transmitted can be carried out by anyconversion algorithm capable of producing the necessary projections,whereby the aforementioned method is only a simplified, theoreticalillustration of the conversion through spherical projections.

The conversion of the display data is advantageously carried out by thetarget system, which knows the definition of its display system 22 andwhich takes locally, in real time, with a minimum latency time, theother parameters specific thereto as the observation conditions of theobserver. In such a case, the target system must also possess thedefinition of the conditions under which the source system generates thedisplay data, in particular the parameters of the display system, forexample transmitted at the start of the connection with a non-variabledata set of the operating data to the device of the source and targetsystems, in addition to the position and orientation of observation ofthe user 90 in the source display system 12.

However, the conversion of the display data can be partially carried outby the source system, or by another system, provided that the targetsystem transmits the operating data required for the processingoperations on the display data in order to produce the images to bedisplayed on the display system of said target system.

In such a case, as mentioned above, the conversions applied to thedisplay data requiring the use of variables specific to the targetsystem 20, in particular the position and direction of observation ofthe user 91 of said target system, are carried out on the digitalprocessing system 21 of said target system, which is used to synchronisethe images displayed by the target display system 22 with said variablesspecific to the target system.

In one embodiment, the source system 10, or another ancillary computer,carries out a first conversion of the operating data intonon-dimensional operating data, independent from the structure of aviewing system to be used to display the images, for example byattributing the features of each image point associated with a directionof said image point determined in the form of spherical coordinates in asystem of axes attached to the observation point in the display system12 of said source system. The target system 20 thus uses thenon-dimensional operating data received to produce display data suitablefor its display system 22 by attributing, at each point of a screen in agiven direction of the observation conditions in the target displaysystem 22, the features attributed to the image point corresponding tothe same direction in the non-dimensional display data.

In the example embodiment described in detail above, the targetimmersive system allows the observer 91 to correctly view arepresentation of a virtual environment substantially simultaneously tothe generation of said representation by another immersive system.

In other embodiments, a source system transmitting the representation ofthe virtual environment is not necessarily associated with displaymeans. Such a source system is, for example, a recording of the displaydata carried out on an image synthesis system, which may or may not bean immersive system. Such a source system is, for example, a systemdelivering images of a real world, recorded or in real time, virtualisedby said system for transferring display data. Such a source system canalso be a system combining the capacity to produce synthesis imagescombined with images of a real world in line with an augmented realitylogic.

When a stereoscopic visualisation of the virtual environment is producedin an immersive system, each eye sees a different image corresponding todifferent observation conditions that can result in the need to convertthe display data for each of the observation conditions, at least whenthe two source and target systems are configured to display the imagesof the virtual environment with depth perception.

In these embodiments, the display data comprises virtual or virtualisedimages, which are representations of the virtual environment viewed in awindow of observation of the source system, equivalent to the displaysystem of the source immersive system of the embodiment described above.

The display data received from the source system by the target immersivesystem is interpreted in order to reconstruct, in the display system ofthe target immersive system, a representation of the environment viewedin the source window of observation.

Thus, the observer in the target immersive system is presented with astable representation of the representation of the environment viewed bythe source system while ensuring the consistency of the images displayedin the display system of said target immersive system with those of thesource window of observation via which this environment is or wasgenerated and/or viewed.

The target digital processing system 21 has the capacity to synthesisedisplay data suited to its own display system, which can advantageouslybe exploited in order to ease understanding and/or enhance the immersionof the observer of the target system. Thus, the target immersive systemcomprises, if necessary, all or part of the following features, whichcan be combined in the target immersive system provided that they arecompatible with one another:

areas of the display system of the target immersive system, not coveringthe images transmitted by the source system in the display data, displaya background generated by the computing means of said target immersivesystem, in particular to improve the visibility or legibility of therepresentation displayed.

the background comprises one or more patterns from the group consistingof: a colour, a plain grey or black; differently coloured, grey or blackareas, the directions of the separations and/or transitions whereofcorrespond to privileged directions of the environment; one or moretextures.

a texture is superimposed over the image of the window of observation.Such a texture increases, if necessary, the perception quality of therepresentation of the environment by the user of the target immersivesystem by producing a representation corresponding to a customaryperception of the environment.

the computing means of the target immersive system are configured toinlay one or more interface elements in the display of the targetdisplay system, represented as one-, two- or three-dimensional objects.In this way, the user of the target immersive system has a set offunctions that he/she can access through said interface elements suchas, for example, image freezing functions, recording functions, andannotation functions.

a position and/or dimensions of the images of the source display datarepresented in the display system of the target immersive system are afunction of a position from which, and/or of a direction in which, inthe display system of said target immersive system, the observerimmersed in said target immersive system is looking at said displaysystem of the target immersive system. In this manner, the movements ofsaid observer are taken into account to correct the images displayed andmaintain the view with an accurate perspective.

at least one part of the images of the source display data is kept ondisplay in the target display system when said images are theoreticallyoutside of a display area of the target display system, said at leastone part of the image of the window of observation being represented asmaintained against an edge of said display area of the target displaysystem in a direction in the system of reference of said target displaysystem to which an observer of the target immersive system shoulddisplace a direction in which he/she is looking or should displace theorientation in the virtual environment of the target viewing system inorder to move closer to the direction of observation corresponding tothe display data received from the source system. The user of the targetimmersive system therefore does not completely lose the view of theenvironment, even though the representation thereof is theoreticallyoutside of his/her field of vision, allowing him/her to intuitively findthe direction in which he/she must look in order to retrieve, in his/hercurrent position, the representation of the virtual environment.

if the images of the display data transmitted by the source system areoutside of the display area of the display system of the targetimmersive system, a symbolic representation is inlaid in the vicinity ofan edge or is attached to an edge of said display area in a direction,in the system of reference of the target display system, to which theobserver of the target immersive system should displace a direction inwhich he/she is looking or should displace the orientation in thevirtual environment of the target display system in order to move closerto the direction of observation associated with the display datatransmitted by the source system. Thus, the user naturally identifiesthe direction in which the image is located, even when he/she has lostvisibility thereof in his/her target display system.

the target immersive system comprises interaction capacities allowing auser of said target immersive system, through real or virtual controlsaccessible to said user, to interact with the images displayed by thetarget display system.

the interaction capacities comprise the superimposition of annotations,text and/or drawings, over the images displayed.

the immersive system comprises a recorder for recording the imagesdisplayed by the target viewing system during an immersion session.

The present disclosure further relates to a method 200, FIG. 4 , forsharing an immersive environment between a source system 10 and at leastone target immersive system 20, of a device 100, while limiting the dataexchanged both due to the confidential nature thereof and to limit thehardware and software requirements of the target system.

According to the method, a set of information or data is exchangedbetween the source system and one or more target systems, said set ofinformation or data allowing each target system receiving operating datafrom the source system to reproduce and update, in real time, a visualrepresentation of a virtual environment replicating, at least in part,the visual representation of the virtual environment generated by thesource system.

As described above, in the device 100, each of the source system and ofthe one or more target immersive systems that take part in the sharingof an immersion incorporate connection means for connecting totransmission means 30 ensuring the connection of said source system andsaid target immersive systems.

According to the method, in a prior step 210, a set of configurationdata is associated with each of the source system and target immersivesystems.

The configuration data incorporates all information required for thephysical or virtual description of the source system or of the targetimmersive system, and in particular the full-scale reconstructionthereof.

The configuration data of an immersive system comprises, for example:

an identifier identifying the immersive system;

a number of screens;

the sizes and shapes of each screen;

an arrangement of screens in a system of reference of a display system;

a capacity for displaying stereoscopic images and associated conditions;

colorimetric and/or geometric conversions specific to the system and tobe applied to each pixel of an image to be displayed on a screen;

capacities to reproduce one or more positions and directions ofobservation.

This data is adapted as necessary to suit the specific form of thesystem considered and the implementation conditions thereof.

The configuration data, the list whereof provided hereafter is neitherexhaustive nor compulsory, but which must include at least allinformation required for the data exchanges and data processingoperations carried out during the implementation of the method, isdetermined for each immersive or non-immersive system of the device in amanual, automatic or semi-automatic manner depending on the capacitiesof the system considered.

In some embodiments of immersive systems, some of this data can varyover time, for example in the case of a mobile immersive system, theorientation and/or position of the screens of which vary over timeduring an immersion.

In such a situation, the configuration data is transmitted to the one ormore target systems in a manner similar to that of the operating data asdescribed for the following steps.

The configuration data can be incorporated into the operating data.

In a first initialisation step 220, the device 100, grouping togetherthe source system 10 and the target systems 20, via which an immersionmust be produced by the target immersive systems, or shared with thesource system, is initialised.

In this initialisation step, each of the target immersive systems 20 ofthe device initialises a register of the connected source system, saidregister advantageously comprising all of the configuration data of eachof said connected systems, and advantageously all of the configurationdata at least of the source system 10 for the target systems 20.

In practice, the configuration data, in addition to initialisationvalues of variables, initialised by a given immersive or non-immersivesystem, could be limited solely to the data strictly required for thedata transmissions and computations to be carried out by said system.

All of the configuration data of the source system must be accessible toa target immersive system at all times so that said source system cantransmit the display data to said target system, whereby theaccessibility of this data can be achieved, in one embodiment of adevice 100, for example via a record in a database local to the digitalprocessing system of said target immersive system.

In another embodiment of a device 100, a data server 32 a, connected tothe network 31 of the data transmission means 30, and accessible to eachof the source system 10 and target immersive systems 20, comprises adatabase used to store configuration data for each of the immersive ornon-immersive systems of said device, at least as regards that requiredduring the initialisation step, and each of the immersive systems duringthis initialisation step receives the configuration data from theserver, at least the configuration data required by the immersivesystems in view of the conversions that must be carried out on thedisplay data.

Advantageously, regardless of the method of implementing this firststep, the database can be updated during the implementation of themethod as a function of the connection, disconnection or role change ofat least one immersive system of the network.

In an environment-generation step 230, which step is independent andcarried out in a recurring manner when the source system 10 is inoperation, source operating data of the visual representations of avirtual environment is generated on said source system.

The source operating data comprises:

the “observation conditions data”

the “display data”.

The observation conditions data comprises the position from which andthe direction in which, each position and direction capable of beingmeasured or assumed, the user is looking in the source display system 12at a given moment in time, or in which images have been generated, forexample by an image capture device capturing a real environment that isthen virtualised. This data is taken into account in the generation ofthe representation of the virtual environment for a user of the sourcesystem immersed in said environment and is used in the construction ofthe images displayed. In the absence of measured values, the positionsand/or the direction are assumed, for example by identifying an idealposition and/or orientation for using the display system, or a meanposition and/or orientation if a plurality of users can be accommodated,or an imposed position and/or orientation if the immersive systemencourages the one or more users to move to a specific position and/ororientation.

In one embodiment, the display data, computed for each display cycle asa function of a frame rate of said display data, is acquired, oncecomputed, by a software application executed in the digital processingsystem 11 of the source system.

In another embodiment, the display data is acquired during thetransmission thereof to the source display means 12, for example by aconnection to the video link 13 of video equipment 14 between the sourcedigital processing system 11 and the source display means 12.

In one embodiment, if the source immersive system displays stereoscopicimages, the display data acquired is acquired for only one of theobservation conditions, for example the display data corresponding to asingle eye, or in stereo, as a function of the capacity or incapacity ofthe target system to reproduce images in stereoscopic mode or as afunction of options chosen by an operator of the target system. The dataflow can thus be reduced, in addition to the bandwidth needs of the datatransmission means 30.

In one embodiment, if the source immersive system estimates and usespositions and orientations of a plurality of users simultaneously, thedisplay data is acquired for each of the observation conditions andassociated with the corresponding observation conditions in theoperating data.

The video equipment 14 is thus used to acquire display data during thetransmission thereof to the source display system 12, for example byreading signals corresponding to the images over the video link 13,converts said images into a format suitable for the transmission thereofand transmits said images via the data transmission means 30 of thedevice.

At the end of this step 230, the source operating data is sent, directlyor indirectly, by the source system to the users of the informationcontained in said source operating data. The users are, for example,each of the target immersive systems that are connected to said sourcesystem or to an ancillary computer 32 b connected to the network 31 thatreceives the data for the retransmission thereof to the target systems,possibly after having carried out a processing operation on theoperating data.

In a second conversion step 240, the source operating data is convertedas a function of the configuration data of a target immersive system,and as a function of variables generated 242 by said target immersivesystem, in particular the observation data corresponding to theeffective observation conditions in the display system 22 of said targetimmersive system.

During this second step, the following operations are carried out:

Full-scale 3D reconstruction, relative to the target viewing system, ofthe geometric configuration of the source display system in order toobtain a virtual source display system without images, i.e. independentfrom images that are displayed on the one or more screens of said sourcedisplay system;

Display of the associated display data on each of the screens of thevirtual source display system in order to obtain a complete virtualrepresentation of the state of the displays of the source systemdescribed by the display data received;

Repositioning of the virtual source display system relative to theobserver using the target system such that the data of the virtualsource observation conditions, corresponding in the virtual sourcedisplay system to the real observation conditions data in the realsource display system, corresponds to the effective target observationconditions data, at least for the position of observation;

Synthesis of the images constituting all of the display data of thetarget system by the digital processing means of the target system as afunction of the target observation conditions data, using the data ofthe environment reproduced on the target system from the operating dataof the source system.

Advantageously, in one embodiment, the virtual 3D reconstruction of thesource display system, without any images displayed on display means ofthe virtual source system, can be cached by the digital processingsystem of the target immersive system, and thus be reused for subsequentiterations.

According to the display data conversion principle of the method, theobservation conditions data of the virtual environment of the sourcesystem is the same as the observation conditions data of the observer 91in the virtual environment displayed in the virtual source displaysystem on the target system, whereby the visual representation of saidvirtual environment is reproduced for this purpose. This condition isforced such that the images generated by the source system 10 can beviewed without deformation by the observer 91 in the target displaysystem 22.

The display data initially computed by the source system thus does notneed to be recomputed for new observation conditions in the targetsystem, whereby the observation conditions, as regards the position anddirection of observation, are virtually superimposed in the virtualenvironment of the source system and in the virtual environment of thetarget system.

All of the data and programs required by the digital processing means ofthe source system for computing the display data therefore do not needto be replicated on the target system, unlike in the prior art.

In specific cases, for example when taking into account stereoscopicvision, thus implementing two separate observation points, all of theobservation conditions data can be duplicated in order to correspond toeach of the observation points, or transmitted for a single observationpoint only, whereby the observation conditions for the second point arelimited to relative position data of the second point relative to thefirst, for example the distance and direction of the second pointrelative to the first point, thus limiting the volume of the observationconditions data to be transmitted.

The observation data can also correspond to a fictive observation point,for example a cyclopean eye, the observation conditions for each of thepoints being limited to relative position data of each of the realobservation points relative to the fictive point.

In one embodiment, all or part of the operating data transmitted by thesource system is frozen either by the source system before thetransmission thereof, or by the target immersive system upon receiptthereof.

This can involve display data, observation conditions data, or a subsetof observation conditions data.

In such a case, the frozen data is either no longer transmitted by thesource system, or is transmitted with constant values, or is onlytemporarily no longer taken into account by the target system and thelast operating data received and processed by the target system isfrozen.

Freezing is controlled by a command from one of the source or targetsystems, for example upon a command from the user 90, or from theobserver 91, or from an operator of the source system or of the targetsystem. The order can also affect the source system, which is thusfrozen and, in such a case, the target system is subject to the freezingof the concerned data, or can only affect the target system which, insuch a case does not necessarily involve freezing of the source system,but only an interruption in the taking into account of changes in thedata concerned and delivered by the source system.

Upon activation of this data-freezing step 241, the possibility ofupdating the images on the target immersive system by processing theoperating data frozen in said freeze operating mode is preserved,whereby said target immersive system can, in such a case, recompute, inreal time, the display data for the images to be displayed by the targetdisplay system as a function of changes to the observation conditions insaid target display system in order to preserve a correct representationof the frozen virtual environment.

In this mode of operation, an observer 91 can move within the targetviewing system without the representation of the virtual environmentbecoming unstable. The observer 91 can thus more easily implementpointing or annotation methods, well known by one of ordinary skill inthe art, impacting the source system, for example within the context ofcollaborative works on the virtual environment, even though such methodscan be applied when the freeze function is not activated.

It is also possible to maintain, for the user 90 of the source system,an accurate perception of the virtual environment generated by thesource immersive system, while preserving, in the target immersivesystem, a correct and stable view by the observer 91 of said virtualenvironment placed in this frozen condition despite variations in theobservation conditions in said source system.

The display data in the target immersive system is thus interpreted,when the corresponding data is frozen, as if the virtual environment wascompletely static and the user of the source system was no longermoving, thus resulting in a kind of 3D acquisition of the state of saidsource system.

Through specific commands, the freezing step can also concern all datarelative to the observation conditions, or only a subset of this data.For example, during a freezing step, an operator, a user or an observercan choose whether or not to freeze the observation data positionvariables and whether or not to freeze the observation data orientationvariables.

Advantageously, the data displayed by the virtual source display systemno longer varies, and the image points of said virtual source displaysystem, on which the pointing operations and/or annotations are carriedout, are constant.

In one embodiment, a step 243 of recording the source operating data isactivated.

Advantageously, in one embodiment, said pre-recorded source operatingdata is used by the processing system as source operating data, thusallowing a pre-recorded immersion to be replayed on the target system,which could be said source system.

In a third display step 250, all of the display data resulting from theconversion is transmitted to the target display system 22, the operatingdata whereof was taken into account during the conversion of the imagesgenerated by the source system.

In order to form and display a visual representation of an immersiveenvironment in real time to an observer having a target immersivesystem, which is a copy of the visual representation of the immersiveenvironment generated by the source system, the method involves circlingback to the second step 240 after the third step 250.

The cycle with which circling back takes place in order to display a newrepresentation of the virtual environment on the display system of thetarget system, the time of which cycle can be restricted by thecomputations performances of the digital processing systems of each ofthe source and target systems, as well as by the performances of thedata transmission means through which the data is exchanged between saidsource and target systems, is repeated each time the target immersivesystem acquires operating data corresponding to a representation of thevirtual environment on the source system.

Provided that it has not been paused by activation of the data freezingstep 241, the computation is repeated, advantageously as quickly as thedigital processing systems of the source and target systems allow, atleast to provide an observer 91 with a perceived immersion that isconsistent with the generation thereof by the source system, for examplealmost simultaneous with that of the user 90 of the source system whensaid source system is an immersive system.

As stated, the notion of observation conditions combines the notions ofthe position of observation and/or of the direction of observation.These positional and directional parameters can be deduced frommeasurements or analyses. For example, the direction of observation canbe deduced from a measurement of the position of the two eyes of a useror of an observer.

Previously assumed or determined observation conditions can also be usedfor either the source system or a target immersive system, or for both,whereby the implementation of the method allows the displays to beadapted by taking into account differences between the two systems.

The present disclosure as described in the case of a source system 10comprising a multi-screen display system 12 of the CAVE type and asingle target immersive system 20 comprising a display system 22 with asingle screen, is capable of comprising alternatives without leaving theprinciples of the present disclosure disclosed in detail in the exampledescribed.

The device can comprise a source system and any number of targetimmersive systems, as illustrated in FIG. 3 of a device 100 comprisingthree target immersive systems 20 of different types, which cansimultaneously reproduce an environment, even a virtual environment,generated by the source system in the target systems.

The present disclosure allows an immersion to be shared in numerousconfigurations of immersive systems, in particular of display systems ofsaid immersive systems, FIG. 3 illustrating the possible configurationsin a non-limiting manner.

In one embodiment, the source system and a target immersive system bothcomprise a multi-sided display system. Advantageously, the immersivesystems have, in such a case, systems for measuring the position of theobservation point and of the direction of observation of the user or ofthe observer.

In other embodiments, the source system comprises a multi-sided displaysystem and a target system comprises a viewing system of the headsettype.

The viewing systems of the headset type implement screens that arephysically very close to the eyes of the headset user, but which areprovided, in order to remain usable, with optical systems enablingcollimation, which places a virtual image, in this case considered asdefined in geometrical optics, of the surface of the screen at asufficient distance from the eye. It is this virtual image that is thusconsidered to be the image displayed in the viewing system.

In a first mode of operation of this embodiment, the observer using theheadset is placed in the virtual environment containing the sourcesystem reproduced at exactly the same position and in the sameorientation as those of the user of the source system in the sourcesystem. In an alternative embodiment, only the source orientation aboutthe axis defined by the centre of the two eyes is not taken into accountto give a little more freedom to the observer. Advantageously, in thismode, the observer in the target system views exactly what is beingviewed by the user of the source system.

In a second mode of operation of this embodiment, the observer using theheadset is placed in the virtual environment containing the sourcesystem reproduced at exactly the same position as that of the user ofthe source system in the source system. Advantageously, in this mode,the observer in the target immersive system can look in other directionsdifferent from that of the user of the source system.

In other embodiments, the source system comprises a display system ofthe headset type.

The configuration information thus includes a description of the reversegeometric transformation to the geometric transformation associated withthe pixels of the images intended for each of the two eyes in additionto the field of view associated with the headset.

The target immersive system receives the display data directly acquiredby the acquisition system and applies the geometric transformationdescribed in the configuration information thereto in order to recoverflattened images intended for the left eye and for the right eye,without the optical deformations often required for displaying in thistype of immersive system of the headset type.

In one associated embodiment, the source immersive system is of theheadset type and the target immersive system is also of the headsettype. The conversion carried out by the target system consists ofplacing a moving window about the observer in the target system, in avirtual environment, in which window the content is displayed, saidcontent originating from the source system, the size of the window beinga function of the features of the source system so as to at leastcorrespond to the field of view rendered by said source system.

In a first mode of operation, the window is displayed constantly in theobserver's field of view, thus imposing that the position andorientation of said observer in the virtual environment correspondexactly to the position and orientation of the user of the source systemin the source system.

In yet another mode of operation, only the position of the observer inthe target system is restricted in the virtual environment. The observercan orient his/her look in any of the directions, even if he/she onlyperceives the content viewed by the user of the source system when thedirections in which they are both looking are sufficiently close to oneanother.

The source system does not necessarily comprise a source display system,insofar as the operating data comprises all of the observationconditions data associated with the display data of said operating data.

In order to assist the observer of a target immersive system in choosinga direction of observation in a virtual environment, and in the visualperception that he/she has of the virtual environment, all of therepresentation conditions whereof he/she does not have full controlover, symbolic representations are advantageously superimposed over thevisual representation of the virtual environment shown on the targetimmersive system to provide the observer with an orientation aid and aidin selecting a direction of observation.

These symbolic representations comprise, for example, the graphicalmaterialisation of a sphere or of a grid associated with therepresentation of horizontal surfaces, for example a floor, and/orvertical surfaces, for example a wall.

Such symbolic representations, which can possibly be materialised solelyon a temporary basis, for example when instructed by the observer, orunder certain conditions, for example in the case of a fast evolution inthe observation conditions of the source system, assist the observer foreasier selection of the direction of observation and for locatinghis/her position in the virtual scene.

Such graphical elements incorporated into the field of view of theobserver will show the latter in which direction he/she must look toretrieve the image viewed by the user of the source system, i.e. how tolook in the same direction.

In an alternative to these embodiments, the display data of prior imagesdisplayed in the virtual environment of said observer can take time todisappear, thus allowing the content currently viewed according to thecurrent direction in which said user is looking to be superimposed inhis/her field of view, with the prior content viewed in the previousdirections in which said user was looking. If said observer is notlooking in exactly the same direction as said user, he/she could thusperceive a larger portion of the virtual environment viewed by saiduser.

In another associated embodiment, the source system is of the headsettype and the target system is a conventional flat screen, possiblystereoscopic. Advantageously, in this embodiment in particular, theconversion of the display data originating from said headset as afunction of the position data and/or orientation originating from saidheadset allows the portion of content of the virtual environment visiblethrough the display system of the source system to be positioned in thevirtual environment of the target system in a stabilised manner, thusreducing the impact of the frequent head movements of the user of thesource system.

Advantageously, a processing operation allowing such stabilisation canbe implemented regardless of the source and target systems used, and ismainly beneficial if the source system has means for measuring theorientation of the observation point.

In one mode of operation of this embodiment, the window of the virtualenvironment of the target immersive system, in which the imagecorresponding to the visible source virtual environment portion isdisplayed, is positioned on a geometric shape similar to a fixed andinvisible sphere centred on the head of the observer, the positionwhereof at the surface of the sphere is a function of the direction inwhich the user of the source system is looking, whereby said functioncan be linear or otherwise. In order to overcome the absence of apositioning system on a conventional screen, the sphere can rotate aboutitself in order to track the look of the user of the source immersivesystem when this user is looking in a direction that is initiallysituated outside of the field of the target display system.

Advantageously, such a mode of operation gives the observers of thetarget system the feeling that the source virtual environment isrevealed progressively as the user of the source system looks indifferent directions, in the manner of a torch that would only light thepart of the environment towards which it is pointed at any one time.

By extension from the embodiments described above, the source immersivesystem can also be an augmented reality viewing headset, in which casethe environment taken into account by the acquisition means of saidsource system is a combination of the virtual displays and of the imagesof the real scene, both of which are superimposed.

In one embodiment, the display means of the source immersive system arevirtual, whereby the challenge involves the computing of the content tobe displayed on a target immersive system by the digital processingmeans of the source immersive system without being concerned withdisplaying the information on the display system of the source immersivesystem. Advantageously, the source immersive system can use the positionand orientation of the observer in the target immersive system as theposition and orientation for the computation of the display data, whichposition and orientation of the observer in the target immersive systemare transmitted to said source system via the network connection means.

In one mode of operation of this embodiment, the source system generatesa non-dimensional image consisting of a 360° projection of the virtualenvironment, resulting in an image or a set of images that can beconverted by the target immersive system, while taking into account thedifference between the observation conditions used by the source systemand the effective observation conditions of the observer in the targetimmersive system at the time the image is displayed.

In another mode of operation of this embodiment, the source systemcomputes a set of display data corresponding to the geometricconfiguration of the display system of the target immersive system. Theconversions carried out by the target immersive system take into accountthe discrepancy between the position used by the source system and theeffective position of the observer in the target immersive system at thetime the image is displayed.

Although the present disclosure has been disclosed in a detailed mannerin the case of the implementation of display systems using flatrectangular or square screens, an immersive system comprising othershapes of screens can be implemented in the device and in the methodboth as a source system and as a target system.

For example, one or more curved screens can be implemented in a displaysystem. In such a case, according to the present disclosure, thenecessary conversions are carried out while taking into account thefeatures of the curve of the surface on which, in the case of the sourcesystem, an image is displayed, and in the case of the target system, animage is to be displayed. The present disclosure can, in particular inthis situation, adapt an image to a different curve between a screen ofthe source system and a screen of the target system, since theprocessing system associated with the target system has all of thegeometric information associated with the source system for virtuallyconstructing exactly the same screen with the same curves.

In one embodiment, independently from the type of system implemented asa source system, the display system of a target immersive systemcomprises a single conventional flat screen having, if necessary,stereoscopic display capacities.

Such an embodiment allows a plurality of spectators to experience, viaimmersion in the target system, an experience of the user immersed inthe source system. In one mode of operation of this embodiment, theposition and orientation of observation of the user of the target systemare assumed such that they correspond to the default position andorientation in the target system.

In one alternative embodiment on a model similar to the previousembodiment, the display system of the target system is a mobile ortransportable device such as a tablet, smartphone or laptop computer.

In one additional mode of operation applicable to the previousembodiments, the display system and/or the processing system of thetarget immersive system and/or of the source system are associated withequipment, generally combining hardware and software, implemented so asto interact with the visual representations on the display system, whichwill be jointly referred to as the “interaction means”. Theseinteraction means can take on any form provided that they allow thecontent and/or the behaviour of the images to be influenced via thedisplay system and/or the processing system. These interaction meanscomprise, for example in a non-exhaustive manner, terminals with director indirect tactile capacities, a keypad, a pointer such as a mouse or atrackball, digital pens, a 3D pointing device, a gyroscopic pointingdevice, or eye tracking systems, etc. The function for freezing thedisplay data on the target system can thus be activated thanks to theseinteraction means and the one or more observers on the target system canuse the interaction means of said target system to point and/orannotate, with text and/or with drawings and/or with symbols, on thesurface of the frozen image, then record these annotated images via asuitable interface.

Such possibilities for interactions, pointing operations and annotationsare advantageously implemented on each of the source and target systemssuch that the user on the source system and the observer on the targetimmersive system can use the capacities thereof.

In one embodiment, the pointing operations and annotations carried outon a target or source system are also transmitted by the communicationmeans in a digital data format to the other or to a plurality of otherinterconnected target immersive systems such that the pointingoperations and annotations, carried out by an observer or by the user,can be inlaid in the visual representations displayed on each of theother immersive systems concerned.

In order to simplify the systems and prevent the need to implement adevice for measuring the position of the head and eyes of a user or ofan observer, these parameters can be estimated as functions ofmeasurements or of observations that are more or less accurate, yetsufficient for obtaining a reconstruction of the image of the immersiveenvironment that is acceptable to the observer.

For example, the target system can be a smartphone, the screen whereofforms the display system and a camera whereof on the front face of saidsmartphone tracks, via a dedicated software application, the position ofthe head or eyes of the observer.

In all cases, as understood from the detailed description of oneembodiment, the parameters of the source and target observationconditions are required in order to formulate the conversions of theimages of the source system into consistent images on the target system.According to whether one or the other of the source or target systems,or both thereof, are equipped or not with a system for determining thevariable values of the parameters regarding the observation conditions,the values of the parameter are taken into account or, in the absencethereof, assumed values are taken into account as a function of thedisplay means and observation conditions.

For example, the display system of the target immersive system can be ascreen associated with tactile capacities such as interaction means. Theobserver can thus use these interaction means to change the positionand/or direction of observation parameters and thus dynamicallydetermine a position and/or a direction of observation according towhich he/she observes the virtual representation of the source immersiveenvironment. The tactile capacities can be replaced by a mouse-typedevice. The 2D or 3D display control using these interaction means iswell known to one of ordinary skill in the art. The interaction means ofthe target immersive system thus allow the observer to control a subsetof the observation conditions for the target immersive system.

Advantageously, according to the present disclosure, all types ofimmersive systems described can be combined in a more or less complexdevice which is not restricted to a single source system/target systempairing.

The present disclosure can also apply to different types of virtualenvironments. The virtual environment can be a three-dimensionalenvironment.

The virtual environment can also be a two-dimensional environmentrepresented by still or moving, stereoscopic or non-stereoscopic images.

In the case of stereoscopic images, knowledge of the properties of theimage capture appliance can allow the correct proportions to bereproduced for the observer on the target system.

Thus, according to the device and method of the present disclosure, thereproduction of an environment generated on a source system in one or aplurality of target immersive systems is obtained, without the necessarytransmission of information other than that corresponding to theconfiguration data and operating data generated by the source system.

Despite the differences between the target immersive system and thesource system, the environment perceived by a user of the source systemis reproduced in a manner that is consistent with regards to an observerof the target system, who thus benefits from the immersion experience inthe virtual environment of the source system.

This result is obtained with minimum requirements in terms of datatransmission and in terms of the cost of adapting existing systems.

What is claimed is:
 1. A device for sharing an immersion in a virtualenvironment, comprising: a source immersive system comprising a sourcedisplay system, said source immersive system delivering operating datafor a visual representation of the virtual environment, said operatingdata comprising display data generated at said source immersive systemand corresponding to images of said visual representation displayed onthe source display system of said source immersive system and saidoperating data further comprising observation conditions including anobservation position and facing direction of a head of a user underwhich the visual representation of the virtual environment wasgenerated; at least one target immersive system, comprising a digitalprocessing system delivering images to at least one display system ofsaid target immersive system; said device being characterised in that itcomprises: means for transmitting the operating data delivered by thesource immersive system to the at least one target immersive system;means for converting the display data generated at said source immersivesystem, representative of images of the visual representation of thevirtual environment delivered by the source immersive system associatedwith data on the observation conditions, in order to build imagesdisplayed in the at least one display system of the target immersivesystem, such that the set of images displayed by said at least onedisplay system of said target immersive system is the result ofprocessing operations that enhance the immersion on said targetimmersive system in the display data upon passage from the observationconditions transmitted by the source immersive system to effectiveobservation conditions in the at least one display system of said targetimmersive system; said enhancement of the immersion includingcompensation of visual deformations resulting from one of processing ofthe source immersive system generated display data on different displaysystems and/or according to different observation conditions; and thedisplay data conversion effects reconstructing a virtual sourceenvironment, which is a virtual reconstruction of the physicalenvironment of the source display system, and forcing an observationpoint of an observer in the at least one display system of the targetimmersive system to take a coincident position in the virtual sourceenvironment as an observation point of a user in the source displaysystem, while allowing the observer in the at least one display systemof the target immersive system to choose a different observationorientation, wherein software for partial processing of display data isexecuted on a digital processing system of the source immersive system,or on an ancillary computer connected to a network via which data istransmitted between the source immersive system and the at least onetarget immersive system, said software converting the display datadelivered by said source immersive system, representative of images ofthe visual representation of the virtual environment of said sourceimmersive system, into display data corresponding to non-dimensionalimages that are independent of a structure of a viewing system that isto display the images, said display data corresponding tonon-dimensional images being transmitted to the at least one targetimmersive system, wherein the non-dimensional images correspond toimages projected onto an inner wall of a sphere, at the centre of whichsphere an observation point of the source immersive system is placed, inorder to form non-dimensional images in a solid angle corresponding tothe images of the display data of the source immersive system, capableof reaching four Pi steradians.
 2. The device according to claim 1,wherein the conversion of the display data comprises a reconstruction ofa 3D virtual representation of the source display system of the physicalenvironment of the source display system, a position of the observationpoint of the observer in the at least one display system of the targetsystem being forced, for the conversion of the display data, to take thesame position in said 3D virtual representation of said source displaysystem as the position of observation of the user in the source displaysystem.
 3. The device according to claim 1, wherein the source immersivesystem comprises a measuring system for measuring, in real time, thedirection of observation, and/or the position of observation, in thesource display system of the source immersive system, of the user thatwould be immersed in the virtual environment of said source immersivesystem, and the at least one target immersive system comprises ameasuring system for measuring the direction of observation,respectively and/or the position of observation, in the at least onedisplay system of said target immersive system, of the observer thatwould be immersed in the virtual environment displayed on said targetimmersive system.
 4. The device according to claim 1, wherein theconversion of the display data originating from the source immersivesystem as a function of the position data and/or orientation of saidsystem allows the content of the virtual environment visible through thesource display system of the source immersive system to be positioned inthe virtual environment of the target immersive system in a stabilisedmanner.
 5. The device according to claim 1, wherein the display dataprocessing software for building images displayed by the at least onedisplay system of the at least one target immersive system is executedon computing means of said target immersive system.
 6. The deviceaccording to claim 1, wherein the source immersive system comprisesequipment for acquiring a signal carrying display data, generated by thesource immersive system, and which transmits, in a digital data format,said display data corresponding to the signal acquired, directly orindirectly, to the at least one target immersive system.
 7. The deviceaccording to claim 1, wherein the source immersive system comprisessoftware, executed on a digital processing system, for acquiring contentof the display data of said source immersive system, after the displaydata has been computed, and which transmits, in a digital data format,said content of the display data acquired, directly or indirectly, tothe at least one target immersive system.
 8. The device according toclaim 1, comprising a data recording system configured to record theoperating data generated by the source immersive system and fortransmitting said operating data to at least one target immersive systemin delayed time.
 9. The device according to claim 1, wherein: the sourceimmersive system further comprises image processing software and asource display system; at least one target immersive system furthercomprises software for image synthesis and for generating a visualrepresentation of a virtual environment in the form of images displayedon one or more screens of the at least one display system of said targetimmersive system, and comprises equipment and/or software for acquiringthe display data corresponding to the images displayed on the at leastone display system of said target immersive system, such that each ofsaid immersive systems can alternate between being a source immersivesystem and a target system.
 10. The device according to claim 1, whereina display system and a digital processing system of at least one targetimmersive system and/or of the source immersive system are associatedwith interaction means configured such that they modify, via the displaysystem and/or the processing system of the given target immersive systemor source immersive system, the content and/or the behaviour of theimages displayed by the display system of said source immersive systemor of the given target immersive system.
 11. The device according toclaim 10, wherein the interaction means comprise a freeze command forselectively activating and deactivating the freezing of all or part ofthe display data and/or of the observation conditions used to generatethe images to be displayed by the display system of the source immersivesystem and/or of the target immersive system.
 12. The device accordingto claim 11, wherein the interaction means of the target immersivesystem comprise a freeze command for freezing a subset of observationconditions in the display system of the source immersive system and/orin the display system of the target immersive system.
 13. The deviceaccording to claim 10, wherein the interaction means of at least onetarget immersive system are moreover configured for pointer use and/orfor the annotation of the images displayed by the display system of saidtarget immersive system.
 14. The device according to claim 13, whereindata characterising the pointing operations or annotations formed onimages of the target immersive system are transmitted via transmissionmeans to the source immersive system and/or to at least one otherconnected immersive system.
 15. The device according to claim 10,wherein the interaction means comprise one or more touch-sensitivesurfaces or surfaces that are sensitive to the presence of a hand orfinger, and/or one or more pointers.
 16. The device according to claim1, wherein the source display system of the source immersive system, andthe at least one display system of the at least one target immersivesystem, each belong to one of the categories implementing flat screensand/or curved screens from the group: multi-sided display systems;virtual reality, augmented reality or mixed viewing headsets;multi-screen display systems; screens; screens carried by a user orobserver.
 17. The device according to claim 1, wherein at least onetarget immersive system is situated in a location that is remote fromthe source immersive system, the physical separation of the two systemsbeing such that the user of said source immersive system and theobserver of said target immersive system are not capable ofcommunicating with one another without using technical communicationmeans.
 18. The device according to claim 1, wherein at least one targetimmersive system is situated in the vicinity of the source immersivesystem, the physical separation being such that the user of said sourceimmersive system and the observer of said target immersive system cancommunicate directly with one another without any physical barrier. 19.A method for sharing an immersion in a virtual environment of anobserver in a target immersive system, comprising the steps of:generating, independently from the target immersive system, operatingdata for a visual representation of the virtual environment, saidoperating data comprising display data corresponding to images of saidvisual representation and comprising observation conditions including anobservation position and facing direction of a head of a user ( )associated with said display data; displaying, on a display system ofthe target immersive system, images representing the virtualenvironment; characterised in that said method comprises, for each imageor set of images to be displayed, between the generation step and thedisplay step, a conversion step, carried out at least partially on thetarget immersive system, for converting the display data of the virtualenvironment generated in the generation step independently from thetarget immersive system, said conversion step comprising thedetermination of the effective observation conditions of the observer inthe display system of said target immersive system and the conversion ofthe display data associated with the observation conditions of thedisplay data generation step, into display data corresponding to saideffective observation conditions of the observer; forcing an observationpoint of the observer in the display system of the target immersivesystem to take a coincident position in the virtual environment as anobservation point of the user associated with said display data, whileallowing the observer in the display system of the target immersivesystem to choose a different observation orientation; and enhancing theimmersion by compensating for visual deformations resulting from one ofprocessing of the display data on different display systems and/oraccording to different observation conditions, wherein software forpartial processing of display data is executed on a digital processingsystem of a source immersive system, or on an ancillary computerconnected to a network via which data is transmitted between the sourceimmersive system and the at least one target immersive system, saidsoftware converting the display data delivered by said source immersivesystem, representative of images of visual representation of the virtualenvironment of said source immersive system, into display datacorresponding to non-dimensional images that are independent of astructure of a viewing system that is to display the images, saiddisplay data corresponding to non-dimensional images being transmittedto the at least one target immersive system, wherein the non-dimensionalimages correspond to images projected onto an inner wall of a sphere, atthe centre of which sphere an observation point of the source immersivesystem is placed, in order to form non-dimensional images in a solidangle corresponding to the images of the display data of the sourceimmersive system, capable of reaching four Pi steradians.
 20. The methodaccording to claim 19, wherein each image point of an image converted inthe conversion step for display by the display system of the targetimmersive system, is determined as a function of at least one effectiveobservation point in the display system of the target immersive systemin order to preserve, to within a constant proportionality factor forthe entire image at a given moment in time, a same relative direction ofobservation relative to any other image point of said converted image,observed from said effective observation point, as the relativedirection between said image points in the display data of the visualrepresentation of the virtual environment generated in the generationstep, delivered by a source immersive system and comprising the imagedata and the data on the observation conditions associated with saidimage data.
 21. The method according to claim 19, wherein the generatingstep for generating the display data of the representation of thevirtual environment is carried out on a source immersive system, whichsource immersive system is: an image generation system for a virtualdisplay, a system for broadcasting a stream of real or virtual imagesgenerated in real time or recorded, or an immersive system in which auser is immersed.
 22. The method according to claim 21, wherein theconversion step comprises a reconstruction of a 3D virtualrepresentation of the source display system of a physical environment ofa source display system of the source immersive system.
 23. The methodaccording to claim 19, wherein the conversion step for convertingdisplay data is carried out entirely on the target immersive systemafter a step of transmitting the display data of the representation ofthe virtual environment to said target immersive system, said datahaving been generated in the generation step.
 24. The method accordingto claim 19, wherein the generation step comprises a display datapartial conversion step, before a step of transmitting the partiallyconverted display data to the target immersive system, in which partialconversion step the display data is converted without being dependent onvariable data of the display conditions in the target immersive system.25. The method according to claim 19, wherein the conversion stepcomprises a freezing step for freezing the display data of therepresentation of the virtual environment or for freezing theobservation conditions, generated during the generation step.
 26. Themethod according to claim 25, wherein the data of the observationconditions in the display system of the target immersive system continueto be taken into account during the display data freezing or observationconditions freezing step.
 27. The method according to claim 19,comprising an initialisation step in which the target immersive systeminitialises a register comprising data on conditions under which thedisplay data is generated during the generation step.